Transmission drive establishing control

ABSTRACT

A pressure control for controlling the pressure in a fluid motor that operates a drive establishing device of a vehicle transmission. The control operates to provide smooth drive establishment by controlling the pressure in the fluid motor during drive engagement at a level that causes a transmission component whose speed changes during the drive establishment to change speed at a substantially constant rate.

United States Patent Borman et al. 1 1 Feb. 15, 1972 [54] TRANSMISSIONDRIVE ESTABLISHING [56] References Cited CONTROL UNITED STATES PATENTSInventors: August II. Borman, Livonia; Lawrence E. Green, Ann Arbor;Quinby E. Wonn, Plymouth, all of Mich.

Assignee: General Motors Corporation, Detroit,

Mich.

Filed: May 13, 1970 Appl. No.: 36,847

US. Cl. ..l92/l03 F, 192/85 AA, 192/103 C Int. Cl ..Fl6d 23/10 FieldofSearch ..l92/l03 C, 103 F, 109 F, 85 R, 192/54 2,739,679 3/1956 Randol192/54 Primary Examiner-Mark M. Newman Assistant Examiner-Randall HealdAttorney-W. E. Finken, A. M. Heiter and R. L. Phillips [57] ABSTRACT Apressure control for controlling the pressure in a fluid motor thatoperates a drive establishing device of a vehicle transmission. Thecontrol operates to provide: smooth drive establishment by controllingthe pressure in the fluid motor during drive engagement at a level thatcauses a transmission component whose speed changes during the driveestablishment to change speed at a substantially constant rate.

2 Claims, 3 Drawing PATENTEBFEB 15 I972 3. 642. 1 O7 TRANSMISSION {aATTORNEY TRANSMISSION DRIVE ESTABLISHING CONTROL This invention relatesto transmission drive establishing device controls and more particularlyto pressure controls for the fluid motors that operate vehiculartransmission drive establishing devices.

The control according to the present invention is illustrated in atransmission having a friction brake that is operable to establish adrive on the supply of fluid pressure to a fluid that engages the brake.Fluid pressure supply to the fluid motor for drive establishment andalso fluid pressure exhaust therefrom for releasing the drive isnormally controlled by a shift valve. The pressure control according tothe present invention includes a control member having a speed thatchanges during the establishment of the drive. This control memberoperates a pressure regulator to cause the pressure of the fluidsupplied to the fluid motor to be controlled with time at a level thateffects a substantially constant rate of change in the speed of thiscontrol member during the establishment of the drive. Thus, inertia isused to control the rate at which the drive is established. In addition,a centrifugal effect is combined with the inertial effect on thepressure regulator valve to assure smooth engagement for light throttleshifting and also heavy throttle shifting by providing for the averagerate of change of speed to vary from a low rate during light throttleshifting to a high rate duringheavy throttle shifting.

An object of the present invention is to provide a new and improvedtransmission drive establishing device control.

Another object is to provide a pressure control for the fluid motor of atransmission drive establishing device wherein the pressure iscontrolled with time at a level that effects a substantially constantrate of change in the speed of a member in the transmission whose speedchanges during the establishment of the drive.

Another object is to provide a fluid pressure control that controls thedrive-engaging pressure in a transmission at a level that effects asubstantially constant rate of speed change of a transmission memberthat changes speed during the drive establishment with this rate varyingwith the speed of this transmission member.

Another object is to provide both an inertial effect and a centrifugaleffect for controlling the pressure buildup in the fluid motor of atransmission drive establishing device so that the rate of change ofspeed of a transmission component whose rate of change of speed iscontrolled by operation of this device is changed at a rate that ismodulated by the speed of this transmission component.

Another object is to provide in a transmission a drive that isestablished by operation of a fluid motor wherein the pressure level inthe fluid motor to establish the drive is controlled by an inertiaeffect and also centrifugal effect to provide for smooth transmissionshifting.

These and other objects of the present invention will be more apparentfrom the following description and drawing in which:

FIG. 1 schematically illustrates a transmission arrangement includingdrive train and control having the transmission drive establishingdevice control according to the present invention.

FIG. 2 is a longitudinal sectional view of an actual construction of thetransmission drive establishing device control in the transmissionarrangement shown in FIG. 1.

FIG. 3 is a view taken on the line 33 in FIG. 2.

The transmission drive establishing device control according to thepresent invention is shown incorporated for use in the transmissionarrangement shown in FIG. 1. This transmission arrangement is operableto provide three forward speed range drives, neutral and a reversedrive.

The transmission s drive train shown in FIG. 1 comprises an input shaftwhich is adapted to be connected by a conventional hydrodynamic torqueconverter to the vehicle's engine, both the converter and engine notbeing shown. The input shaft 10 is connected to a drum 12 which may beclutched by a clutch 13 to a hub 14 that is connected to a shaft 15.Input shaft 10 may also be clutched by a clutch 16 to a drum 18 that isconnected to a sleeve shaft 20 through which shaft 15 extends.

The clutch 13 comprises drive plates 22 which are connected by splinesto drum 12 and are adapted to engage driven plates 23 which areconnected to hub 14. A fluid motor 24 has a fluid chamber 25 that, whensupplied with fluid pressure, provides for forcing a piston 26 to engagethe clutch plates 22 and 23 to clutch shaft 10 to shaft 15. When chamber25 is exhausted of fluid pressure, the clutch 13 is released with thepiston 26 being returned to its release position by retraction springs,not shown.

The clutch 16 as shown in both FIGS. 1 and 2 comprises drive plates 27which are connected by splines to drum l2 and are adapted to engagedriven plates 28 which are connected by splines to drum 18. A fluidmotor 30 has a chamber 32 which, when supplied with fluid pressure,provides for forcing a piston 34 to engage plates 27 and 28 to clutchinput shaft 10 to shaft 20. When fluid pressure is exhausted fromchamber 32, the clutch I6 is released permitting retraction springs 37to return the piston 34 to its release position.

The shafts 15 and 20 are connected to the transmissions gearing whichcomprises a pair of planetary gearsets 38 and 39. The gearset 39comprises an annular sun gear 40, agear ring 41 and a planet carrier 42carrying pinions 44 in mesh with sun gear and ring gear 41. Ring gear 41is connected to shaft 15, sun gear 40 is connected to shaft 20 andcarrier 42 is connected by a drum 45 to a shaft 46 which is thetransmissions output shaft.

The gearset 38 comprises an annular sun gear 48, a'ring gear 49 and aplanet carrier 50 carrying pinions 51 in mesh with sun gear 48 and ringgear 49. Sun gear 48 is connected to shaft 20 and thus also to the othersun gear 40 and ring gear 49 is connected to drum 45 and thus to carrier42 and output shaft 46.

A one-way brake 54 is for preventing reverse rotation of carrier 50 ingearset 38. One-way brake 54 comprises an outer race 55 which isconnected by a drum 56 to carrier 50. This brakes inner race 58 isgrounded to the transmissions housing which is generally designated as59. The one-way'brake 54 may be of any suitable conventional type andoperates to permit free forward rotation of carrier 50 and preventreverse rotation thereof. A band brake 60 grounded to the transmissionhousing 59 and operated by any suitable fluid pressure operated motor isadapted to engage drum 56 to hold carrier 50 against rotation in eitherdirection.

The sun gears 40 and 48 may be selectively prevented from only reverserotation by a brake 61 and a one-way brake 62 in series therewith. Thebrake 61 comprises plates 64 which are connected by splines to thetransmission housing 59 and are adapted to engage plates 66 whichare-connected by splines to outer race 68 of the one-way brake 62. Afluid motor 69 has a chamber 70 which, when supplied with fluidpressure, provides for forcing a piston 71 to engage plates 64 and 66 tobrake the outer race 68 of the one-way brake 62. This oneway brakesinner race 72 is connected to drum 18 and thus to shaft 20 and sun gears40 and 48. Thus, when brake 61 is engaged, the one-way brake 62 operatesto prevent reverse rotation of sun gears 40 and 48. The one-way brake 62may be of any suitable conventional type such as the sprag type shown. Aband brake 76 grounded to the transmission housing 59 and operated byany suitable fluid pressure operated motor is adapted to engage drum 18to hold sun gears 40 and 48 I against rotation in either direction.

The drive-establishing devices in the above-described transmission drivetrain may be operated to establish three forward speed range drives,neutral and a reverse speed range drive by a transmission control 78which may be of any suitable conventional type. One suitabletransmission control for this transmission arrangement is disclosed inU.S. Pat. No. 3,321,057 entitled "Transmission and Control System"issued to Winchell et al. on May 23, I967. The transmission control 78by operation of a manual valve and shift valves controls the delivery offluid at a regulated pressure to the fluid motors that operate thevarious drive-establishing devices to effect the different transmissiondrives. For neutral, all of the clutches and brakes are caused to bereleased by the transmission control 78 and no power can be transmittedfrom input shaft to output shaft 46.

The first and lowest forward speed range drive is established by thetransmission control 78 delivering fluid pressure via a passage 79 tofluid motor 24 to engage clutch l3. Torque from the forwardly rotatinginput shaft 10 is delivered through the engaged clutch 13 to drive ringgear 41 forwardly. Assuming a load on output shaft 46 and thus oncarrier 42, this carrier tends to remain stationary so that sun gears 40and 48 are driven in reverse. In gear unit 38, torque input to pinions51 from sun gear 48 tends to cause carrier 50 to rotate backwardly, butsuch rotation is prevented by one-way brake 54. Pinions 51 thereforedrive ring gear-49 and thus output shaft 46 at a reduced speed in theforward direction. Because of the action of one-way brake 54, powercannot be transmitted backwardly through the drive train. Thus, forengine braking in low drive, the band brake 60 is engaged by thetransmission control 78 providing fluid pressure supply to this brakesfluid motor to hold carrier 50 against rotation in the forwarddirection.

The second and next higher forward speed range drive is established byretaining engagement of clutch 13 and engaging brake 61 bythevtransmission control 78 delivering fluid pressure via a passage 80to fluid motor 69. Torque thus remains applied to ring gear 41 but nowwith sun gear 40 held against reverse rotation by one-way brake 62,carrier 42 and thus output shaft 46 are driven forwardly at a reducedspeed but in a speed range higher than that obtainable in the low drive.Since one-way brake 62 permits forward rotation of sun gear 40,,powercannot be transmitted in the reverse direction.

Thus, for engine braking in this drive, the band brake 76 is engaged bythe transmission control 78 delivering fluid pressure to this brakesfluid motor. Then, with sun gear 40 thus held against forward rotation,engine braking is thereby made available in this drive.

The third and highest forward speed range drive is established bymaintaining engagement of clutch l3 and engaging clutch 16 by thetransmission control 78 supplying fluid pressure via a passage 81 tofluid motor 30. The brake 61 may remain engaged since one-way brake 62permits forward rotation of drum 18 and thus permits forward rotation ofsun gears 40 and 48. Since both ring gear 41 and sun gear 40 are drivenat the same speed and in the same direction, gearset 39 is locked up toprovide a 1:1 speed ratio or direct drive to drive output shaft 46.

The above sequential operation demonstrates how upshifts are effected.Downshifts are effected by reversing this sequence.

Reverse speed range drive is obtained by engaging clutch 16 by thetransmission control 78 supplying fluid pressure to fluid motor 30 andin addition engaging the band brake 60 by the transmission control 78also supplying fluid pressure to this brake's fluid motor. With clutch16 thus engaged, the sun gear 48 is driven forwardly and since carrier50 is held by brake 60, the pinions 51 drive ring gear 49 and connectedoutput shaft 46 in the reverse direction and at a reduced speed.

The transmission drive establishing device control according to thepresent invention is incorporated in the abovedescribed transmissionarrangement to provide control over the pressure in fluid motor 69 andalso over the pressure in fluid motor 30 to provide for smoothestablishment of the intermediate speed range drive and also smoothestablishment of the high-speed range drive. The present controlcomprises, as shown schematically in FIG. 1 and as shown in detail inFIGS. 2 and 3, a ring-shaped member 82 which may also be termed aninertia ring for reasons which will become more apparent later. Theinertia ring 82 is piloted on a cylindrical shoulder 83 formed on drum18 and is retained thereon by being sandwiched between the drum l8 andthe outer race 68 of the one-way brake 62 as best shown in FIG. 2.Inertia ring 82 is causedto rotate with drum 18 or to be held stationarywith this drum and is also permitted limited angular movement relativeto this drum by a cylindrical pin 84 which is secured to drum 18 andextends into a circular hole 85 of larger diameter provided in ring 82.An O-ring 86 is mounted in an annular groove provided on the portion ofpin 84 within hole 85 and is preferably made of a material such asrubber or plastic to prevent metaI-to-metal contact between pin 84 andring 82 and thus avoid metal pounding and also reduce the noise of theircontact.

The ring 82 and drum 18 have separate pressure regulator valve means forseparately controlling the pressure buildup in the fluid motors 30 and69. The valve means for fluid motor 69 comprises a bleed or exhaustpassage 87 that is connected to passage 80 and thus to chamber 70 offluid motor 69. As best shown in FIG. 3, the inner surface 88 of inertiaring 82 provides for closing and opening the bleed passage 87 to anexhaust port 89 formed in the inertia ring 82, the bleed passage 87extending radially outward through drum 18 and through the cylindricalsurface of shoulder 83 for this purpose. The exhaust port 89 is open tothe interior of the transmission housing 59 which drains to thetransmission controls sump. A spring 90 mounted in a radially inwardextending pocket 91 in drum 18 biases a ball 92 against a ramp 93provided on the interior of ring 82. As viewed in FIG. 3, the forwarddirection referred to in the description of transmission operationdescribed above is in the counterclockwise direction indicated by thearrow. The spring-biased ball 92 acting against ramp 93 provides atorque urging ring 82 counterclockwise or in the forward, directionrelative to drum 18 to the position shown which will be referred to asthe closed valve position and is determined by the ring 82 contactingthe stop provided by pin 84 with its O-ring 86. In the closed valveposition, the inertia ring 82 acting as a valve member blocks the bleedpassage 87 from exhaust port 89. Thus, in this closed valve position,pressure can build in chamber 70 offluid motor 69 to the full regulatedpressure provided from the transmission control 78. Alternatively, whenthe inertia ring 82 is caused to rotate clockwise or in the reversedirection relative to drum 18 as the result of this rings inertia asdescribed in more detail later, there is provided an openingbetweenbleed passage 87 and exhaust port 89 which opening increases in sizewith increasing relative angular movement ,between these members withthe full extent of this opening in what will be described as the fullyopen valve position being determined by the O-ring 86 on pin 84contacting the opposite side of the wall of hole 85. Thus, there isprovided a variable throttle connection between the bleed passage 87 andexhaust port 89 effective to control the pressure in chamber 70 of motor69. An orifice 97 located in the passage between transmission control 78and passage 80 limits the flow of fluid so that a relatively lowpressure can be achieved in chamber 70 in the fully open valve position.

v The pressure regulator valve means for controlling the pressure influid motor 30 is similar to that for fluid motor 69 and comprises ableed passage 98 that is connected to passage 81 and thus to chamber 32of fluid motor 30. When inertia ring 82 is in the closed valve positionpreviously described, the bleed passage 98 which extends through thesurface of shoulder 83 is blocked from an exhaust port 96 in ring 82 byrings inner surface 88. This permits pressure in chamber 33 to build tothe full value. Alternatively, when the inertia ring 82 movescounterclockwise relative to drum 18 towards the fully open valveposition previously described, the bleed passage 98 is opened to exhaustport 96 by a throttle connection whose flow area increases withincreasing relative movement between ring 82 and drum 18. An orifice 99located in the passage between transmission control 78 and passage 81limits the flow of fluid so that a relatively low pressure can beachieved in chamber 32 in the fully open valve position.

It will now be recalled that in the low speed range drive the sun gear48 and connected drum 18 and thus inertia ring 82 rotate in the reversedirection which is counterclockwise as viewed in FIG. 3 and that thisdrum and thus the inertia ring is braked to a stop to establish theintermediate speed range drive. According to the present invention, thebias of spring 90 provides a torque to normally hold the ring 82 in theclosed valve position against the stop so that in the steady statecondition when there is no acceleration of drum 18, the bleed passage 87is blocked from exhaust port 89. Then when an upshift to theintermediate speed range drive is initiated by the transmission control78 which for this establishment then directs the delivery of fluidpressure to fluid motor 69, the brake 61 starts to engage as pressurestarts to build in chamber 70. During this drive establishment theinertia ring 82 resists deceleration thereof caused by braking of druml8 and this inertia provides an inertia torque that opposes the springtorque on ring 82. According to the present invention, the spring-applied torque is made equal to the inertia-induced torque so that theseopposing torques on ring 82 balance each other to provide regulationover the opening of bleed passage 87 to exhaust port 89 and thusregulation of the pressure in chamber 70 of fluid motor 69. By thistorque balance on ring 82, the deceleration rate of ring 82 that occursduring this drive establishment is made constant or substantiallyconstant since the inertia-induced torque is the product of the ringsmoment of inertia and deceleration rate.

Describing this pressure control in more detail, as fluid is deliveredto chamber 70 and pressure begins to build on filling of this chamber,the engaging force engaging brake 61 causes drum [8 and thus'inertiaring 82 to slow down or decelerate. On such deceleration and with theresulting inertia torque on ring 82 balanced by the spring-appliedtorque, the ring 82 acts to regulate the opening of bleed passage 87 toexhaust port 89 to maintain the pressure in chamber 70 at that valuethat is required to establish a constant deceleration rate of ring 82.For example, if the brake engagement becomes too aggressive the ring 82whose inertia is resisting the forced speed decrease will rotateclockwise relative to drum 18 through a few degrees to open bleedpassage 87 to exhaust port 89 to relieve the brake apply pressure.Alternatively, if the brake engagement is too soft the bleed passage 87will remain blocked by no relative movement of ring 82 to increase thebrake apply pressure. Thus the brake apply pressure is caused toregulate with time during brake engagement at a rate that effects aconstant or substantially constant change in speed or deceleration ofinertia ring 82 with the result that there is provided a very smoothestablishment of the transmissions intermediate speed range drive. Atthe completion of the drive establishment, the inertia torque drops tozero and the spring applied torque again holds the inertia ring 82 inits closed valve position blocking bleed passage 87 from exhaust port 96and thebrake apply pressure is thus at the full value.

It has also been found that if the rate of drive engagement is constantat all engine throttle openings, there may occur firm light enginethrottle shifts and also soft heavy throttle shifts. The rate of driveestablishment provided by the inertial control described previously issubstantially a lineal function if the centrifugal force on ball 92 isnot substantial. To avoid such firm and soft shifts, the mass of ball 92is made a substantial amount so that the centrifugal force acting on theball 92 will modulate the spring torque acting on ring 82 and thus willmodulate the deceleration rate provided by the inertia controlpreviously discussed so that this rate varies with the speed of drum l8and thus during the shift interval. Thus, on the upshift to intermediatedrive and with the drum l8 and thus ball 92 rotating at the initiationof this shift, the centrifugal force on ball 92 provides a significantaddition to the spring force to thereby increase the bias urging closingof the bleed passage 87 to exhaust port 89. This increases the initialrate of pressure buildup in fluid motor 70 so that the deceleration rateof drum 18 starts at an increased or faster rate and decreases withdecreasing drum speed to a slower rate during this transmission shift.It has been found that such centrifugal modulation provides a bettershift feel for the upshift to intermediate drive than inertia controlalone by increasing the average rate of deceleration during high-speedshifts to a greater rate than the average rate of deceleration duringlower speed shifts.

On an upshift from intermediate to the high-speed range drive, the druml8 and thus ring 82 are accelerated from zero speed to input speed.Prior to such an upshift, the inertia ring 82 will be in its closedvalve position shown in FIG. 3 with bleed passage 98 blocked fromexhaust port 96. Then when the transmission control 78 delivers fluidunder pressure to fluid motor 30 and as the clutch 16 starts to engageon pressure buildup in this motor, the drum 18 is accelerated in thecounterclockwise direction. The inertia ring 82 tends to remainstationary with its inertia torque caused by the acceleration opposed bythe spring-applied torque which latter torque resists opening of thebleed passage 98 to exhaust port 96. Thus, there is provided aninertia-controlled level of pressure in fluid motor 30 to engage theclutch 16 similar to that described previously controlling the brake 61.The centrifugal force modulation of the inertia-controlled rate ofengagement of clutch 13 is opposite that provided for brake 61 sincethedrum l8 and thus ring 82 are accelerating from zero speed onestablishment of the high drive whereas they were decelerating on theupshift to the intermediate drive. Thus, on the upshift to high drivethe inertia-controlled acceleration rate is low initially and increaseswith increasing drum speed to a higher rate during this transmissionshift. It has been found.

that such centrifugal modulation provides a better shift feel for theupshift to high dn've than inertia control alone by increasing theaverage rate of acceleration during high-speed shifts to a greater ratethan the average rate of acceleration during lower speed shifts.

The above-described embodiment is illustrative of the invention whichmay be modified within the scope of the appended claims.

We claim:

1. In combination, drive-establishing means operable to establish adrive, fluid motor means for operating said driveestablishing means toestablish said drive, a source of fluid at a predetermined pressure,drive selection control means for controlling delivery of said fluid tosaid fluid motor means to operate said drive-establishing means toestablish said drive and also for exhausting fluid from said fluid motormeans to release said drive, and pressure control means includinginertia means having a speed which changes during the establishment ofsaid drive and centrifugal means having a speed which also changesduring the establishment of said drive for causing the pressure of thefluid in said fluid motor means to be regulated with time at a levelthat effects an inertial controlled rate of change in speed of saidinertia means during the establishment of said drive.

2. In combination, drive-establishing means operable to establish adrive, fluid motor means for operating said driveestablishing means toestablish said drive, a source of fluid under pressure, drive selectioncontrol means for controlling delivery of said fluid to said fluid motormeans to operate said drive-establishing means to establish said driveand also for exhausting fluid from said fluid motor means to releasesaid drive, pressure control means including rotary inertia means havinga speed that changes during the establishment of said drive for causingthe pressure of the fluid in said fluid motor means to be controlledwith time at a level that effects a controlled rate of change in thespeed of said inertia means during the establishment of said drive, saidpressure control means further including a rotary member having a speedthat changes during the establishment of said drive, means limitingmovement of said inertia means relative to said rotary member, saidinertia means and said rotary member having valve means operable toprevent fluid pressure exhaust from said fluid motor means when saidinertia means is in one position relative to said rotary member and alsooperable to provide increasing pressure exhaust from said fluid motormeans when said inertia means moves in one direction from said oneposition to another relative position, and biasing means includingspring means and centrifugal force effect means rotatable with saidrotary member for normally holding said inertia means in said onerelative position when the speed of said rotary member is substantiallyconstant and for permitting said inertia means to move by its inertia insaid one direction toward said other relative position to regulate thepressure in said fluid motor means when the speed of said rotary memberis changing during establishment of said drive.

1. In combination, drive-establishing means operable to establish adrive, fluid motor means for operating said driveestablishing means toestablish said drive, a source of fluid at a predetermined pressure,drive selection control means for controlling delivery of said fluid tosaid fluid motor means to operate said drive-establishing means toestablish said drive and also for exhausting fluid from said fluid motormeans to release said drive, and pressure control means includinginertia means having a speed which changes during the establishment ofsaid drive and centrifugal means having a speed which also changesduring the establishment of said drive for causing the pressure of thefluid in said fluid motor means to be regulated with time at a levelthat effects an inertial controlled rate of change in speed of saidinertia means during the establishment of said drive.
 2. In combination,drive-establishing means operable to establish a drive, fluid motormeans for operating said drive-establishing means to establish saiddrive, a source of fluid under pressure, drive selection control meansfor controlling delivery of said fluid to said fluid motor means tooperate said drive-establishing means to establish said drive and alsofor exhausting fluid from said fluid motor means to release said drive,pressure control means including rotary inertia means having a speedthat changes during the establishment of said drive for causing thepressure of the fluid in said fluid motor means to be controlled withtime at a level that effects a controlled rate of change in the speed ofsaid inertia means during the establishment of said drive, said pressurecontrol means further including a rotary member having a speed thatchanges during the establishment of said drive, means limiting movementof said inertia means relative to said rotary member, said inertia meansand said rotary member having valve means operable to prevent fluidpressure exhaust from said fluid motor means when said inertia means isin one position relative to said rotary member and also operable toprovide increasing pressure exhaust from said fluid motor means whensaid inertia means moves in one direction from said one position toanother relative position, and biasing means including spring means andcentrifugal force effect means rotatable with said rotary member fornormally holding said inertia means in said one relative position whenthe speed of said rotary member is substantially constant and forpermitting said inertia means to move by its inertia in said onedirection toward said other relative position to regulate the pressurein said fluid motor means when the speed of said rotary member ischanging during establishment of said drive.